Articulating surgical stapling apparatus with pivotable knife bar guide assembly

ABSTRACT

A surgical stapling apparatus includes a shaft assembly, an end effector secured to the shaft assembly, a firing assembly, and an articulation assembly. The firing assembly includes a drive beam and a flexible knife bar assembly that are selectively advanceable through the end effector for firing the end effector. The articulation assembly has an articulation link assembly and a pivotable bar guide assembly. The articulation link assembly is coupled to the end effector and actuatable to cause the end effector to articulate relative to the shaft assembly. The pivotable bar guide assembly supports the flexible knife bar assembly and includes a proximal guide assembly and a distal guide assembly that are pivotably coupled together. The proximal guide assembly is pivotably coupled to the shaft assembly. The distal guide assembly is pivotably coupled to the end effector.

TECHNICAL FIELD

This disclosure relates to surgical stapling apparatus, devices and/orsystems for performing surgical procedures and methods of use thereof.

BACKGROUND

Surgical stapling apparatus that clamp, cut and/or staple tissue arewell known in the art. Such surgical stapling apparatus include endeffectors having two elongated jaw members used to capture or clamptissue. One of the two jaw members usually carries a staple cartridgethat houses a plurality of staples positioned in rows, while the otherof the two jaw members has an anvil for forming the staples as thestaples are driven from the staple cartridge. For instance, in linearsurgical stapling apparatus, a stapling operation is effectuated by acam bar, a drive sled or other similar mechanism having a cam memberthat travels longitudinally through channels defined in the staplecartridge and acts upon staple pushers in the channels to sequentiallyeject linear rows of staples from the staple cartridge. A knife, oftensupported on a drive beam, is movably positioned between the linear rowsof staples such that when the surgical stapling apparatus is positionedabout tissue and actuated, the tissue is joined and/or simultaneously ornearly simultaneously cut.

Some surgical stapling apparatus include reloads (sometimes referred toas loading units) and handle assemblies. The reloads may includearticulatable end effectors with various articulation angles relative tothe handle assemblies. With linear stapling, greater articulation isalways desirable with a shorter dead space (e.g., distance from anarticulation joint to where a staple line starts). To facilitatearticulation, surgical stapling apparatus can include rotatable barguides to guide knife bars. As the bar guides rotate when the jawmembers are articulated, the bar guides can cause the knife bars todistally advance where the greater the articulation, the greater thedistal advancement. Advancing of the drive beam requires increased deadspace to provide for extra movement and/or require the articulation anddrive beam travel to be timed together (e.g., simultaneous two motormovement).

SUMMARY

This disclosure details surgical stapling apparatus including a barguide assembly that prevents bar buckling and maintains length duringarticulation such that a drive beam of the surgical stapling apparatusdoes not travel upon articulation. Advantageously, the bar guideassembly may be doubled hinged to enable increased articulation andmechanical articulation independent of drive beam travel. Further, thesurgical stapling apparatus may include an articulation link with aguide ramp that reduces bend tightness and dead space. In particular,the guide ramp may enable the bar guide assembly to rotate outwardlybefore bending inwardly to provide a gradual bend. The associated bendpath enables the drive beam to be positioned farther back than instapling apparatus with standard bend paths, thereby providing shorterdead space. This bending movement maintains the drive beam lengthconstant during articulation whereby the drive beam does not moveforward during articulation. This bending movement enables articulationand linear drive to be independent of one another, for example, at leastup to approximately 50 degrees of articulation relative to a centrallongitudinal axis of the surgical stapling apparatus. This disclosurealso reduces the need for homing the surgical stapling apparatus after aloading unit is secured to the surgical stapling apparatus.

In accordance with one aspect, this disclosure is directed to a surgicalstapling apparatus that includes a shaft assembly, an end effectorsecured to the shaft assembly, a firing assembly, and an articulationassembly. The firing assembly includes a drive beam and a flexible knifebar assembly that are selectively advanceable through the end effectorfor firing the end effector. The articulation assembly has anarticulation link assembly and a pivotable bar guide assembly. Thearticulation link assembly is coupled to the end effector and actuatableto cause the end effector to articulate relative to the shaft assembly.The pivotable bar guide assembly supports the flexible knife barassembly and includes a proximal guide assembly and a distal guideassembly that are pivotably coupled together. The proximal guideassembly is pivotably coupled to the shaft assembly. The distal guideassembly is pivotably coupled to the end effector.

In aspects, the pivotable bar guide may pivot in response to anactuation of articulation link assembly. The articulation link assemblymay include a proximal articulation link and a distal articulation linkthat are pivotably coupled together. The distal articulation link mayhave a proximal end portion coupled to a distal end portion of theproximal articulation link, and a distal end portion coupled to aproximal end portion of the end effector. The proximal articulation linkmay include a guide ramp positioned to engage the pivotable bar guidewhen the end effector articulates relative to the shaft assembly.

In aspects, the proximal guide assembly may include a proximal boss thatpivotably couples to the shaft assembly. The proximal guide assembly mayinclude a distal hoop defining a boss opening therethrough. The distalguide assembly may include a proximal boss that is received within theboss opening of the distal hoop of the proximal guide assembly topivotably couple the proximal and distal guide assemblies together. Thedistal guide assembly may include a distal boss that pivotably couplesto a proximal end portion of the end effector. The proximal end portionof the end effector may include a mounting assembly. The mountingassembly may define a boss bore therein that receives the distal boss ofthe distal guide assembly to pivotably couple the distal guide assemblyto the mounting assembly.

In aspects, the pivotable bar guide assembly may define a centralpassage therethrough that slidably receives the knife bar assembly.

According to another aspect, this disclosure is directed to a surgicalstapling apparatus including a housing assembly, an adapter assemblyextending from the housing assembly, and a reload selectively attachableto the adapter assembly. The reload supports an end effector on a distalend portion of the reload. The reload includes a firing assembly and anarticulation assembly. The firing assembly includes a drive beam and aflexible knife bar assembly that are selectively advanceable through theend effector for firing the end effector. The articulation assembly hasan articulation link assembly and a pivotable bar guide assembly. Thearticulation link assembly is coupled to the end effector and actuatableto cause the end effector to articulate relative to the shaft assembly.The pivotable bar guide assembly supports the flexible knife barassembly and includes a proximal guide assembly and a distal guideassembly that are pivotably coupled together. The proximal guideassembly is pivotably coupled to the shaft assembly. The distal guideassembly is pivotably coupled to the end effector.

In accordance with yet another aspect, this disclosure is directed to areload for a surgical stapling apparatus. The reload includes a shaftassembly, an end effector, an articulation link assembly, and apivotably bar guide assembly. The end effector supports a drive beam anda flexible knife bar assembly that are selectively advanceable throughthe end effector for firing the end effector. The articulation linkassembly is coupled to the end effector and actuatable to cause the endeffector to articulate relative to the shaft assembly. The pivotable barguide assembly is configured to bend the flexible knife bar assemblywhen the end effector articulates relative to the shaft assembly. Thepivotable bar guide assembly includes a proximal guide assembly and adistal guide assembly that are pivotably coupled together. The proximalguide assembly is pivotably coupled to the shaft assembly. The distalguide assembly is pivotably coupled to the end effector.

Other aspects, features, and advantages will be apparent from thedescription, the drawings, and the claims that follow.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate aspects of the disclosure and,together with a general description of the disclosure given above, andthe detailed description of the aspect(s) given below, explain theprinciples of the disclosure, wherein:

FIG. 1 is a perspective view of a surgical stapling apparatus inaccordance with the principles of this disclosure;

FIG. 2 is an enlarged, perspective view of the indicated area of detailillustrating an end effector of the surgical stapling apparatus of FIG.1 in an unarticulated position;

FIG. 3 is another perspective view illustrating the end effector of FIG.2 in an articulated position;

FIGS. 4-6 are enlarged, perspective views of distal portions of thesurgical stapling apparatus of FIG. 1 , the distal portions shown withportions thereof removed for clarity;

FIG. 7 is a perspective view, with parts separated, of a distal portionof the surgical stapling apparatus of FIG. 1 ;

FIG. 8 is a perspective view of a bar guide assembly of the surgicalstapling apparatus of FIG. 1 ;

FIG. 9 is a perspective view, with parts separated, of an upper guideassembly of the bar guide assembly of FIG. 8 ;

FIG. 10 is a perspective view of a lower guide assembly of the bar guideassembly of FIG. 8 ;

FIG. 11 is an enlarged, cross-sectional view as taken along section line11-11 of FIG. 2 ;

FIG. 12 is a cross-sectional view as taken along section line 12-12 ofFIG. 11 with the surgical stapling apparatus shown in the unarticulatedposition;

FIG. 13 is a view of FIG. 12 illustrating the surgical staplingapparatus in a first articulated position; and

FIG. 14 is a view of FIG. 12 illustrating the surgical staplingapparatus in a second articulated position.

DETAILED DESCRIPTION

Aspects of the disclosed surgical stapling apparatus are described indetail with reference to the drawings, in which like reference numeralsdesignate identical or corresponding elements in each of the severalviews. As commonly known, the term “clinician” refers to a doctor, anurse, or any other care provider and may include support personnel.Additionally, the term “proximal” refers to the portion of structurethat is closer to the clinician and the term “distal” refers to theportion of structure that is farther from the clinician. In addition,directional terms such as front, rear, upper, lower, top, bottom, andthe like are used simply for convenience of description and are notintended to limit the disclosure attached hereto. As used herein, theterm “endoscopic” is used generally used to refer to endoscopic,laparoscopic, arthroscopic, and/or any other procedure conducted througha small diameter incision or cannula.

As used herein, the terms parallel and perpendicular are understood toinclude relative configurations that are substantially parallel andsubstantially perpendicular up to about + or −10 degrees from trueparallel and true perpendicular.

In the following description, well-known functions or constructions arenot described in detail to avoid obscuring the present disclosure inunnecessary detail.

Further, although the surgical stapling apparatus are generally shownand described herein in connection with a linear surgical staplingsystem for brevity, the disclosed surgical stapling apparatus caninclude any powered, manual, or robotically-controlled surgical staplingsystems such as a circular stapler, a transverse stapler, or an openstapler. For a detailed description of the structure and function ofexemplary surgical stapling systems, one or more components of which maybe included, or modified for use with the disclosed aspects, referencemay be made to U.S. Pat. Nos. 9,713,470; 8,806,973; 8,256,656;8,157,152; 8,070,033; 7,819,896; 7,770,774; 7,334,717; 7,128,253;5,964,394; and 5,915,616, the entire contents of each of which areincorporated herein by reference.

With reference to FIGS. 1-12 , a surgical stapling apparatus 10 of thisdisclosure includes a housing assembly 12 (which may include one or morehandles that may be manually actuatable to fire surgical staplingapparatus 10), an adapter assembly 14 secured to housing assembly 12 andextending distally from housing assembly 12, and a reload 100 secured toadapter assembly 14 and extending distally from adapter assembly 14.Adapter assembly 14 and reload 100 define a longitudinal axis “X-X” thatextends longitudinally therealong. Reload 100 may be reusable,disposable and/or include one or more reusable and/or disposablecomponents. Housing assembly 12 may be in the form of a powered housingassembly that provides powered actuation of reload 100 via adapterassembly 14.

Reload 100 of surgical stapling apparatus 10 is releasably secured to adistal end portion 14 a of adapter assembly 14 and includes a shaftassembly 102 that supports an end effector 104 on a distal end portionof shaft assembly 102. End effector 104 includes an anvil assembly 106and a cartridge assembly 107 that houses a plurality of fasteners orstaples in a plurality of rows of staple slots 108 a defined in a staplecartridge 108 of cartridge assembly 104. The plurality of rows of stapleslots 108 a are supported on opposed sides of a knife slot 108 c definedthrough staple cartridge 108. Staple cartridge 108 is selectivelyattachable to a support plate 109 that is pivotably coupled to anvilassembly 106 via pivot pins 111. Staple cartridge 108 may be selectivelyremovable from support plate 109 and replaceable. Anvil assembly 106includes an anvil 110 defining a plurality of rows of staple pockets 110a (FIG. 6 ) therein that correspond with the plurality of rows of stapleslots 108 a of staple cartridge 108 so that the plurality of staples canbe dispensed from staple slots 108 a of staple cartridge 108 and formedagainst staple pockets 110 a of anvil 110 upon a firing of surgicalstapling apparatus 10.

Reload 100 of surgical stapling apparatus 10 supports shaft assembly 102on a proximal end portion thereof and end effector 104 on a distal endportion thereof. End effector 104 is pivotably coupled to shaft assembly102 by a mounting assembly 120 that enables end effector 104 toarticulate relative to shaft assembly 102 about an articulation axis“A-A” extending through mounting assembly 120, as indicated by arrows“Z.” In particular, end effector 104 may pivot about articulation axis“A-A” from an unarticulated position (FIG. 2 ), aligned withlongitudinal axis “X-X” of surgical stapling apparatus 10, to anarticulated position (FIG. 3 ). Mounting assembly 120 includes an uppermounting block 122 and a lower mounting block 124 that are pinnedtogether via mount pins 126 extending from upper mounting block 122.Upper mounting block 122 includes an upper coupler pin 122 a extendingtherefrom and lower mounting block 124 includes a lower coupler pin 124a depending therefrom (see FIG. 11 ). Upper coupler pin 122 a pivotablysupports an upper coupling arm 128 and lower coupler pin 124 a pivotablysupports a lower coupling arm 130. Upper and lower coupling arms 128,130 extend from mounting assembly 120 and secure mounting assembly 120to shaft assembly 102. Mounting assembly 120 further defines aproximally-facing concave recess 120 x therein (FIG. 12 ).

Each of upper and lower coupling arms 128, 130 includes an elongatedbody 129 having a hooked proximal end portion 129 a and a distal couplerpin opening 129 b defined therethrough. Elongated body 129 furtherdefines a proximal pin opening 129 c therethrough.

Shaft assembly 102 of reload 100 includes an outer sleeve 102 a and aninner shaft assembly 102 b supported within outer sleeve 102 a. Innershaft assembly 102 b includes an upper shaft housing 1021 and a lowershaft housing 1022 that couple together and define coupler cutouts 1024in outer surfaces of distal end portions thereof. Upper and lower shafthousings 1021,1022 have identical structure and are disposed in mirroredrelation to one another. Coupler cutouts 1024 of upper and lower shafthousings 1021, 1022 are configured to receive hooked proximal endportions 129 a of respective upper and lower coupling arms 128, 130therein for fixedly securing upper and lower coupling arms 128, 130 toupper and lower shafts housings 1021, 1022. The distal end portions ofupper and lower shafts housings 1021, 1022 further define pin apertures1026 therethrough that are disposed in registration with proximal pinopenings 129 c of respective upper and lower coupling arms 128, 130. Thedistal end portion of upper and lower shaft housings 1021, 1022 furtherdefine a distally facing concave recess 1028 therein.

Reload 100 of surgical stapling apparatus 10 further includes a firingassembly 140 having a drive beam assembly 141 and sled 143 that isdisposed in cartridge assembly 107 for dispensing staples therefrom.Drive beam assembly 141 has a proximal end portion that is operativelycoupled to adapter assembly 14 of surgical stapling apparatus 10. Drivebeam assembly 141 has a knife bar assembly 142 and a drive beam 144secured to a distal end portion of knife bar assembly 142 for engagementwith sled 143. Knife bar assembly 142 is flexible and includes aplurality of laminates 142 a coupled together. Drive beam 144 may be inthe form of an I-beam and includes a knife 144 a.

Reload 100 further includes an articulation assembly 150 having anarticulation link assembly 160 and a pivotable bar guide assembly 170that is double hinged.

Articulation link assembly 160 of articulation assembly 150 includes aproximal articulation link 162 having a clevis 164 supported on a distalend portion thereof and a guide ramp 162 a defined in the distal endportion of articulation link 162 adjacent to a proximal end portion ofclevis 164. Articulation link assembly 160 further includes a distallink 166 having a proximal snare 166 a and a distal snare 166 b.Proximal snare 166 a is received by clevis 164 and pinned thereto vialink pin 168. Distal snare 166 b is coupled to a mount pin 126 of uppermounting block 122.

Pivotable bar guide assembly 170 of articulation assembly 150 includesan upper guide assembly 180 and a lower guide assembly 190 that arecoupled together.

Upper guide assembly 180 includes a proximal upper guide 182 and adistal upper guide 184, and lower guide assembly 190 includes a proximallower guide 192 and a distal lower guide 194. Upper guide assembly 180and lower guide assembly 190 having mirrored structure such thatproximal upper guide 182 and proximal lower guide 192 are identical (butinverted versions of one another) and together form a proximal guideassembly 170 p. Distal upper guide 184 and distal lower guide 194 areidentical (but inverted versions of one another) and together form adistal guide assembly 170 d. Given the symmetry of structure between theupper and lower guide assemblies 180, 190, only upper guide assembly 180is described hereinbelow for brevity.

As best seen in FIGS. 8-11 , proximal upper guide 182 of upper guideassembly 180 includes a proximal boss 182 a projecting from an uppersurface thereof and a distal hoop 182 b extending distally from proximalupper guide 182. Distal hoop 182 b defines a boss opening 182 ctherethrough. Proximal upper guide 182 further defines a central passage182 d therethrough. Proximal upper guide 182 further includes distalabutments 182 e depending from distal hoop 182 b.

Distal upper guide 184 of upper guide assembly 180 includes a proximalboss 184 a that is received within boss opening 182 c of proximal upperguide 182 to pivotably couple distal upper guide 184 and proximal upperguide 182 together. Distal upper guide 184 further includes a distalboss 184 b that is received within a boss bore 122 b defined within alower surface of upper mounting block 122 to pivotably couple distalupper guide 184 to upper mounting block 122—notably, a distal boss 184 bof distal lower guide 194 of lower guide assembly 190 pivotably couplesto a boss bore 124 b defined within an upper surface of lower mountingblock 124 as seen in FIG. 11 . Distal upper guide 184 of upper guideassembly 180 further defines a side slot 184 c defined in a proximalportion of distal upper guide 184 adjacent to proximal boss 184 a.Distal upper guide 184 also defines a central passage 184 dtherethrough. Distal upper guide 184 further includes concave sidewalls184 e along a central portion thereof. Central passages 182 d, 184 d ofupper guide assembly 180 are configured to slidably receive knife barassembly 142 of drive beam assembly 141 therethrough.

In use, as best seen in FIGS. 2, 3, and 12-14 , articulation linkassembly 160 can be actuated to distally advance proximal articulationlink 162. Distal advancement of proximal articulation link 162 causesdistal link 166 to distally advance and pivot about link pin 168 andmount pin 126 to which distal link 166 is coupled. The distal andpivoting movement of distal link 166 articulates end effector 104 in afirst direction (e.g., laterally to the right) relative to thelongitudinal axis “X” and shaft assembly 102. As end effector 104articulates in the first direction, proximal guide assembly 170 p pivotsabout proximal bosses 182 a in a second direction opposite to the firstdirection (e.g., laterally to the left) and relative to the longitudinalaxis “X.” The proximal guide assembly 170 p can pivot in the seconddirection until a distal end portion (e.g., distal hoops 182 b) ofproximal guide assembly 170 p engages guide ramp 162 a of proximalarticulation link 162. Guide ramp 162 a enables pivotable guide barassembly 170 to cam therealong and facilitate pivotal movement ofpivotable guide bar assembly 170. Such pivoting movement causes aproximal end portion of distal guide assembly 170 d of pivotable guidebar assembly 170 to pivot with the distal end portion of proximal guideassembly 170 p of pivotable guide bar assembly 170 while a distal endportion of distal guide assembly 170 d pivots in the first directionwith end effector 104. This movement causes pivotable bar guide assembly170 to bend the portion of knife bar assembly 142 disposed withinpivotable bar guide assembly 170 so that upon an actuation of firingassembly 140, knife bar assembly 142 can be distally advanced throughend effector 104 when end effector 104 is disposed in such anarticulated position to fire surgical stapling apparatus 10.

Articulation link assembly 160 can be actuated to proximally moveproximal articulation link 162 so that end effector 104 can bearticulated in the second direction. In particular, proximal movement ofproximal link 162 of articulation link assembly 160 draws distal link166 proximally and pivots end effector 104 such that proximal guideassembly 170 p pivots in the first direction and distal guide assembly170 d pivots in the second direction to thereby bend the portion ofknife bar assembly 142 disposed within pivotable bar guide assembly 170.Again, upon an actuation of firing assembly 140, knife bar assembly 142can be distally advanced through end effector 104 when end effector 104is disposed in such an articulated position to fire surgical staplingapparatus 10. Of course, firing assembly 140 can be actuated to advanceknife bar assembly 142 distally through the end effector 104 when endeffector 104 is in an unarticulated position to fire surgical staplingapparatus 10.

Securement of any of the components of the presently disclosed apparatusmay be effectuated using known securement techniques such welding,crimping, gluing, fastening, etc.

The various aspects disclosed herein may also be configured to work withrobotic surgical systems and what is commonly referred to as“Telesurgery.” Such systems employ various robotic elements to assistthe clinician and allow remote operation (or partial remote operation)of surgical instrumentation. Various robotic arms, gears, cams, pulleys,electric and mechanical motors, etc. may be employed for this purposeand may be designed with a robotic surgical system to assist theclinician during an operation or treatment. Such robotic systems mayinclude remotely steerable systems, automatically flexible surgicalsystems, remotely flexible surgical systems, remotely articulatingsurgical systems, wireless surgical systems, modular or selectivelyconfigurable remotely operated surgical systems, etc.

The robotic surgical systems may be employed with one or more consolesthat are next to the operating theater or located in a remote location.In this instance, one team of clinicians may prep the patient forsurgery and configure the robotic surgical system with one or more ofthe instruments disclosed herein while another clinician (or group ofclinicians) remotely controls the instruments via the robotic surgicalsystem. As can be appreciated, a highly skilled clinician may performmultiple operations in multiple locations without leaving his/her remoteconsole which can be both economically advantageous and a benefit to thepatient or a series of patients. For a detailed description of exemplarymedical workstations and/or components thereof, reference may be made toU.S. Patent Application Publication No. 2012/0116416, and PCTApplication Publication No. WO2016/025132, the entire contents of eachof which are incorporated by reference herein.

Persons skilled in the art will understand that the structures andmethods specifically described herein and shown in the accompanyingfigures are non-limiting exemplary aspects, and that the description,disclosure, and figures should be construed merely as exemplary ofaspects. It is to be understood, therefore, that the present disclosureis not limited to the precise aspects described, and that various otherchanges and modifications may be effected by one skilled in the artwithout departing from the scope or spirit of the disclosure.Additionally, the elements and features shown or described in connectionwith certain aspects may be combined with the elements and features ofcertain other aspects without departing from the scope of the presentdisclosure, and that such modifications and variations are also includedwithin the scope of the present disclosure. Accordingly, the subjectmatter of the present disclosure is not limited by what has beenparticularly shown and described.

What is claimed is:
 1. A surgical stapling apparatus, comprising: a shaft assembly; an end effector secured to the shaft assembly; a firing assembly including a drive beam and a flexible knife bar assembly that are selectively advanceable through the end effector for firing the end effector; and an articulation assembly having an articulation link assembly and a pivotable bar guide assembly, the articulation link assembly coupled to the end effector and actuatable to cause the end effector to articulate relative to the shaft assembly, the pivotable bar guide assembly supporting the flexible knife bar assembly and including a proximal guide assembly and a distal guide assembly that are pivotably coupled together, the proximal guide assembly pivotably coupled to the shaft assembly, the distal guide assembly pivotably coupled to the end effector.
 2. The surgical stapling apparatus of claim 1, wherein the pivotable bar guide pivots in response to an actuation of articulation link assembly.
 3. The surgical stapling apparatus of claim 2, wherein the articulation link assembly includes a proximal articulation link and a distal articulation link that are pivotably coupled together.
 4. The surgical stapling apparatus of claim 3, wherein the distal articulation link has a proximal end portion coupled to a distal end portion of the proximal articulation link, and a distal end portion coupled to a proximal end portion of the end effector.
 5. The surgical stapling apparatus of claim 4, wherein the proximal articulation link includes a guide ramp positioned to engage the pivotable bar guide when the end effector articulates relative to the shaft assembly.
 6. The surgical stapling apparatus of claim 1, wherein the proximal guide assembly includes a proximal boss that pivotably couples to the shaft assembly.
 7. The surgical stapling apparatus of claim 6, wherein the proximal guide assembly includes a distal hoop defining a boss opening therethrough, and wherein the distal guide assembly includes a proximal boss that is received within the boss opening of the distal hoop of the proximal guide assembly to pivotably couple the proximal and distal guide assemblies together.
 8. The surgical stapling apparatus of claim 7, wherein the distal guide assembly includes a distal boss that pivotably couples to a proximal end portion of the end effector.
 9. The surgical stapling apparatus of claim 8, wherein the proximal end portion of the end effector includes a mounting assembly, the mounting assembly defining a boss bore therein that receives the distal boss of the distal guide assembly to pivotably couple the distal guide assembly to the mounting assembly.
 10. The surgical stapling apparatus of claim 1, wherein the pivotable bar guide assembly defines a central passage therethrough that slidably receives the knife bar assembly.
 11. A surgical stapling apparatus, comprising: a housing assembly; an adapter assembly extending from the housing assembly; and a reload selectively attachable to the adapter assembly, the reload supporting an end effector on a distal end portion of the reload, the reload including: a firing assembly including a drive beam and a flexible knife bar assembly that are selectively advanceable through the end effector for firing the end effector; and an articulation assembly having an articulation link assembly and a pivotable bar guide assembly, the articulation link assembly coupled to the end effector and actuatable to cause the end effector to articulate relative to the shaft assembly, the pivotable bar guide assembly supporting the flexible knife bar assembly and including a proximal guide assembly and a distal guide assembly that are pivotably coupled together, the proximal guide assembly pivotably coupled to the shaft assembly, the distal guide assembly pivotably coupled to the end effector.
 12. The surgical stapling apparatus of claim 11, wherein the pivotable bar guide pivots in response to an actuation of articulation link assembly.
 13. The surgical stapling apparatus of claim 12, wherein the articulation link assembly includes a proximal articulation link and a distal articulation link that are pivotably coupled together.
 14. The surgical stapling apparatus of claim 13, wherein the distal articulation link has a proximal end portion coupled to a distal end portion of the proximal articulation link, and a distal end portion coupled to a proximal end portion of the end effector.
 15. The surgical stapling apparatus of claim 14, wherein the proximal articulation link includes a guide ramp positioned to engage the pivotable bar guide when the end effector articulates relative to the shaft assembly.
 16. The surgical stapling apparatus of claim 11, wherein the proximal guide assembly includes a proximal boss that pivotably couples to the shaft assembly.
 17. The surgical stapling apparatus of claim 16, wherein the proximal guide assembly includes a distal hoop defining a boss opening therethrough, and wherein the distal guide assembly includes a proximal boss that is received within the boss opening of the distal hoop of the proximal guide assembly to pivotably couple the proximal and distal guide assemblies together.
 18. The surgical stapling apparatus of claim 17, wherein the distal guide assembly includes a distal boss that pivotably couples to a proximal end portion of the end effector.
 19. The surgical stapling apparatus of claim 18, wherein the proximal end portion of the end effector includes a mounting assembly, the mounting assembly defining a boss bore therein that receives the distal boss of the distal guide assembly to pivotably couple the distal guide assembly to the mounting assembly.
 20. A reload for a surgical stapling apparatus, the reload comprising: a shaft assembly; an end effector supporting a drive beam and a flexible knife bar assembly that are selectively advanceable through the end effector for firing the end effector; an articulation link assembly coupled to the end effector and actuatable to cause the end effector to articulate relative to the shaft assembly; and a pivotable bar guide assembly configured to bend the flexible knife bar assembly when the end effector articulates relative to the shaft assembly, the pivotable bar guide assembly including a proximal guide assembly and a distal guide assembly that are pivotably coupled together, the proximal guide assembly pivotably coupled to the shaft assembly, the distal guide assembly pivotably coupled to the end effector. 